The use of optical fibers has become increasingly common in a variety of applications. Optical fibers are particularly useful in the medical arts for apparatus for performing diagnostic and surgical procedures. Lasers and other light sources can used in such applications, but the light must be transmitted into remote body cavities or lumens. The small diameter of optical fibers and their efficient transmission of light provide major benefits in the practicability of such devices.
While the use of optical fibers for these purposes is highly advantageous, there are certain limitations to the use of the fibers that have not thus far been satisfactorily addressed. For example, if the optical fibers are to be used to conduct high energy laser light to a remote location during a surgical procedure, it is important that any break in the light path be detected and the laser light source be immediately interrupted to prevent the escape of light in an uncontrolled manner.
Detection of such a breakage is particularly important in laser angioplasty, in which a catheter containing an optical fiber is inserted into the cardiovascular system and guided to an area of stenosis. After the end of the optical fiber is in place, the laser light emitted from the end of the fiber is directed so as to ablate the stenosis, thereby improving the blood flow through the blood vessel.
The energy transmitted through the fiber is of a sufficient level that if a break in the fiber were to occur and not be detected, significant damage to the vessel and surrounding tissue would occur due to the escape of laser light energy from the break in the fiber. In some circumstances the uncontrolled lasing can endanger nearby personnel.
Furthermore, even if there were no danger from the leakage of light, it would be desirable to detect breakage of the fiber in order to prevent damage to the guiding catheter or surrounding tissue from the broken ends of the fiber.
Also, there are some cases in which light is being transmitted to a remote location by an optical fiber, but there is no simple method of determining that a fiber breakage is the primary cause of the failure in the light to be transmitted along the entire path.
There is at present no available means for detecting such breakage. Prior art glass breakage detection systems assume large panes of glass which shatter upon breakage. Shattering involves large reverberations active over a period of time. These shatter-detectors are responsive to prolonged high frequency signals of high intensity. Optical fibers snap, rather than shatter, and thus produce a very short, impulse-like signal.
Physicians must therefore rely upon the low breakage rate of fibers, and the physicians' personal observation of the progress of the surgery. Hence, there is a need for a reliable means for detecting a breakage in an optical fiber of the type that is utilized to conduct light to a remote location. Furthermore, it would be beneficial if such a breakage detection system would be relatively simple and easily implemented, could provide for the rapid interruption of the light source and would be compatible with a laser angioplasty or surgery apparatus.
Broadly, it is the object of the present invention to provide an improved apparatus and method for the detection of breakage of an optical fiber.
It is a further object of the present invention to provide an apparatus and method for detecting the breakage of an optical fiber which can be used to automatically interrupt the transmission of light through the fiber.
These and other objects of the present invention will be apparent to those skilled in the art from the following detailed description and the accompanying drawings.